Consider the digits 3,5,7,9 . What is the number of 5 -digit numbers formed by these digits in which each of these four digits appears?

Step-by-step solution

Given digits are 3, 5, 7,9 . The number of 5 -digit number formed by these digits in which each of these four digits appears = ^4 C₁ 5! 2! =4 5 4 3 2! 2! =240